The code to look at tty_old_pgrp and send SIGHUP and SIGCONT when it is present only executes when disassociate_ctty is called from do_exit. Make this clear by adding an explict on_exit check, and explicitly setting tty_old_pgrp to 0. In addition fix the locking by reading tty_old_pgrp under the siglock. Signed-off-by: Eric W. Biederman <ebiederm at xmission.com> --- drivers/char/tty_io.c | 8 ++++++-- 1 files changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index bb09e4a..acb2f5d 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -1508,8 +1508,12 @@ void disassociate_ctty(int on_exit) /* XXX: here we race, there is nothing protecting tty */ if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY) tty_vhangup(tty); - } else { - pid_t old_pgrp = current->signal->tty_old_pgrp; + } else if (on_exit) { + pid_t old_pgrp; + spin_lock_irq(¤t->sighand->siglock); + old_pgrp = current->signal->tty_old_pgrp; + current->signal->tty_old_pgrp = 0; + spin_unlock_irq(¤t->sighand->siglock); if (old_pgrp) { kill_pg(old_pgrp, SIGHUP, on_exit); kill_pg(old_pgrp, SIGCONT, on_exit); -- 1.4.4.1.g278f